3rd Annual Meeting of the Australian chapter of the International Neuromodulation Society

The International Neuromodulation Society (INS) recently held its 3rd Annual Scientific Meeting of its Australian chapter at the Perth Convention Centre in Western Australia. The conference, held on the 30th March 2008 was part of the 28th Annual Scientific Meeting of the Australian Pain Society. The theme for this years meeting, Neuromodulation: Technology at the Neural Interface, continued on from the international meeting held in Acapulco, Mexico in December last year. The conference was attended by pain specialists and scientists from around Australia and a special guest speaker, Professor Maureen Simmonds from McGill University in Montreal, Canada. The conference featured some important case studies demonstrating the effectiveness of using peripheral nerve field stimulation (PNFS) and spinal cord stimulation (SCS) in the management of pain conditions. Intrathecal analgesia was a dominant topic of the day with a review of the recent recommendations by an expert panel as well as some encouraging research studies.

Dr Paul Verrrills, the co-medical director of the Metro spinal clinic in Melbourne began the discussions for the day by presenting some encouraging results using the emerging technique of Peripheral Nerve Field Stimulation (PNFS) for the treatment of chronic lower back pain and failed back surgery syndrome (FBSS). His study evaluated 14 patients over 12 months who had undergone this treatment involving the subcutaneous implantation of leads in the areas of pain in the lower back or trunk to stimulate the nerves in these affected regions.² Eleven of the patients reported positive outcomes with significant improvement in overall pain levels as measured using the VAS scale and in the reduction of intake of analgesics. Their study supports a previous case series study that PNFS is a safe and effective treatment option for patients with chronic lower back pain that do not respond to other treatments.² PNFS has the advantage of being a much safer option as there is no risk of neurological side effects and is very successful in reaching the lower back. It also has the added benefit of flexible programming making it a promising emerging new treatment for patients.

An update on the recent developments and challenges faced with the use of spinal cord stimulation (SCS) as a treatment for refractory angina was discussed by Dr Max Majedi, an anaesthesia and pain specialist from Sir Charles Gardiner Hospital in Perth. SCS can reduce the frequency and intensity of angina and randomised control trials (RCT) have demonstrated the efficacy of this treatment in improving quality of life, exercise tolerance and in reducing intake of medication.³ Dr Majedi reported on studies that have shown this treatment to be a cost-effective option which can also reduce mortality and hospitalisation admission rates. Additionally, the procedure is much less invasive than conventional revascularisation therapies such as CABG. He emphasised the role of SCS as a possible treatment option in patients with poor surgical outcomes and those who still have symptoms despite having undergone revascularisation therapy. However, it was pointed out that considerable challenges are being faced in terms of funding, programming and the reluctance of patients as well as cardiologists to utilise this procedure. The importance of education on informing those involved of the benefits of this procedure in the treatment of refractory angina was emphasised.

The recently published update and recommendations for managing pain through intrathecal drug delivery ‘Polyanalgesia Consensus Conference 2007: Recommendations for the Management of Pain by Intra-thecal (intraspinal) Drug Delivery: Report of an Interdisciplinary expert panel’ was presented and reviewed by Dr Charles Brooker, director of the chronic and cancer pain program at the Royal Northshore hospital in Sydney. Dr Brooker highlighted some important changes that had been made in regard to drug therapy for the management of pain conditions. Some important recommendations by the panel included hydromorphone (Dilaudid) being the preferred treatment over morphine because of reduced granuloma formation with maximum advised recommended doses of 10mg/mL and 20mg/mL respectively. Importantly, was the addition of the Ziconotide as a recommended line 1 drug, based on literature demonstrating its effectiveness in selected individuals and its safety in being mixed with other drugs such as opioids. Although a potent analgesic, some concerns with Baclofen (Baclo) were raised in regard to the dangers associated with its sudden withdrawal. Some possible new drugs for the future included adenosine and non-steroidal anti-inflammatory drugs (NSAIDS).⁴ The review provides an algorithm for optimising drug selection and combination through the provision of a set of clinical guidelines, and although they are a useful and informative guide Dr Brooker warned about the possibility of inappropriate use of the guidelines by clinicians to justify the use of an inadvisable trial of treatment therapy. He also pointed out that care must be taken when using pre-manufactured solutions of these drugs.

Continuing on from the discussion of intrathecal analgesics, Dr Marc Russo followed to introduce the concept of spinal analgesic combination chemotherapy, that is, the intra-spinal administration of a combination of analgesic agents which can potentially improve efficacy through synergistic mechanisms. He explained the concept of additivity and synergism between drugs which could be assessed graphically using an isobologram. Opioids such as morphine are strongly synergistic with clonidine and bupivicaine. Dr Russo presented data from his Hunter Clinic showing the effectiveness of this approach where functional outcome and VAS scores were found to be much improved in patients receiving a mixture of multiple analgesic agents.¹ The importance of this is the potential of being able to use lower doses of multiple drugs that act synergistically. However he emphasised the need for further studies to assess the efficacy, safety and potential for granuloma formation in using such combination drug therapies.

One of the highlights of the meeting was the presentation by Professor Maureen Simmons from McGill University of a novel rehabilitative approach in pain management through the use of visual field immersion and virtual reality (VR). This interactive, computer based, multisensory simulation technology has been shown to be effective in reducing pain symptoms, improving mood and enhancing movement in patients suffering from various pain conditions. Her innovative approach revolves around the relationship between pain, mood and movement. By using the virtual environment this simulation technology allows patients to interact in real time using their natural senses and skills. In positively influencing mood, patients are motivated to increase their movement, as any movement is beneficial for the management of pain. By creating a distraction, the experience of visual field immersion can reduce the intensity of the perceived pain. Some promising studies were presented where VR was used to reduce pain and improve function in burn victims, cancer patients and patients with post stroke pain. The potential of VR in exploring fear and reducing anxieties by placing patients in environments which normally elicit fear responses was also highlighted.¹

The role of intrathecal baclofen (ITB) in the treatment of spasticity was presented by Assoc. Prof Barry Rawicki. ITB is often the only effective treatment for generalised or regional spasticity resulting from conditions such as multiple sclerosis, traumatic brain injury, cerebral palsy and stroke. This drug is delivered directly into the subarachnoid space via a pump where it acts as an inhibitory neurotransmitter. Professor Rawicki presented some remarkable results using low dose ITB in the treatment of nine of his patients suffering from Hereditary Spastic Parapesis (HSP). Its success in improving function including gait, seating and controlling painful spasms was effectively shown on some videos of these patients.

The final presentation of the day by Dr Michael Ridding reviewed repetitive transcranial magnetic stimulation (rTMS). This procedure provides a non-invasive means of stimulating the cortex of the brain by fluctuating magnetic fields and can produce long lasting effects on the brain. He discussed the use of rTMS in some preliminary studies in the treatment of depression, stroke and pain conditions.¹

Overall the conference was a success providing insights into new therapies and developments in the field of neuromodulation.

References

1. International Neuromodulation Society abstract book from the 3rd Annual Scientific Meeting of the Australian Chapter of the International Neuromodulation Society. Perth Convention Centre 30 March 2008.
2. Paicius RM, Bernstein CA & Lempert-Cohen C. Peripheral nerve field stimulation for the treatment of chronic low back pain: preliminary results of long-term follow-up: a case series. Neuromodulation 2007; 10(3): 279-290.
3. Lee AW & Pilitsis JG. Spinal cord stimulation: indications and outcome. Neurosurgery focus 2006; 21 (6); E3.1-6.
4. Deer T, Krames ES, Hassenbusch SJ, Burton A et al. Polyanalgesic Consensus Conference Recommendations for the Management of Pain by Intrathecal (Intraspinal) Drug Delivery: Report of an Interdisciplinary Expert Panel. Neuromodulation: Technology at the neural interface 2007; 10(4): 300-328